Operators always confront a problem about how to safely and effectively charge for user's communications. In prior art, when an EPC network charges for user's communication, a PDN Gateway (PGW) and a Serving Gateway (SGW), as forwarding plane devices in the EPC network, are both integrated with a Charging Trigger Function (CTF), a Charging Data Function (CDF) and a Charging Gateway Function (CGF), with which the collection and the credit control of charging information may be achieved, further implementing offline charging or online charging to the user reliably.
In conclusion, the PGW and SGW in the EPC network have not only the essential function as forwarding plane devices, i.e., the forwarding function, but also a logic control function for controlling operations related to charging. The forwarding plane devices in the EPC network therefore have too much load and heavy burden. Furthermore, although the introduction of multiple new technologies such as offloading technology in the EPC network may lead to more overall network functions, the EPC network in which the new technologies are introduced requires test and deployment prior to the introduction which have a long cycle and high cost.
The Open Flow protocol of the network switching model implements the separation between control and forwarding by dividing the network entities into control plane devices and forwarding plane devices. In this case, the control plane devices are used for issuing logic control to forwarding plane devices to instruct the actions of the forwarding plane devices; the forwarding plane devices forward a traffic flow to a certain physical port or logical unit according to the instruction recorded in a flow table issued by the control plane devices. SDN, which is the evolution of the Open Flow protocol, not only has the advantages inherited from the Open Flow protocol, but also implements complex network applications by using software programming technology on the control plane devices, in which situation forwarding plane devices only need to perform the logical control issued from control plane devices without need of any adaptive change. Meanwhile, since the control plane devices of the SDN may be implemented in the form of a combination of a universal server and a universal operating system, or in the form of a universal software programming tool or of a script language such as Python which is easy to transplant and to understand, the support to new technologies of the SDN network becomes quite easy, i.e. the SDN network is more universal and compatible, enabling the deployment cycle for introducing new technologies to be reduced significantly.
There is an eager requirement for a SDN EPC network-based charging method, combining respective features of a SDN network and an EPC network and considering the diversity and versatility of future networks.